You can press and hold any of the hotkeys on a Mac keyboard to temporarily view that function.

Here's a cool trick that could be useful if you use hotkeys or keyboard shortcuts to activate Mission Control, the Dashboard, or Launchpad (i.e. F3/F4).

You might be used to tapping a hotkey once to activate that function and then tapping it again to deactivate (i.e. F3 for Mission Control). However, if you press and hold a hotkey, without releasing, that particular function will only remain active for as long as you hold down the key. For example, press and hold the Mission Control/Exposť hotkey, and it will disappear as soon as you take your finger off the key. Give it a try!

While holding the Mission Control key, you can still select windows, or create new Spaces using the mouse. This works with keyboard shortcuts too, such as Ctrl+Up, the default keyboard combo for Mission Control).

Incidentally, if you're annoyed the Show Desktop mouse gesture has gone in OS X Lion, you can simply hold down Command and tap the Mission Control/Expose hotkey. That will do the same thing.

[crarko adds: I tested some of these on my old MacBook, and they work fine. I'm sure the utility will be even greater with the full size keyboards.]

Or perhaps it's unfair of you to expect free advertising on a Macworld site. So, yes, thanks for submitting the hint, but I'm pretty sure there's something in the Terms of Service on the the site here that prohibits commercial advertising in the posts.

And no, I'm not affiliated with Macworld or OS X Hints, but this just seems like pretty standard stuff in a medium that thrives on paid advertisements.

I've tested it on my brandspanking new MBP with 10.7.2, but it only works for Missioncontrol . It doesn't however work for Launchpad (which is at itself quite useless considering one could simply put everything in the dock)...

Yes. And it is somehow the same when using gesture on a trackpad. For example, if you do a gesture to activate show the desktop (4 fingers swipe up on my Mac) and quickly stop touching the trackpad (the normal way) it shows the desktop and let you chose a file, etc... If you let you finger on the trackpad that it will show the desktop as long as you touch the trackpad and go back to the initial window when removing your fingers.